1. Field of the Invention
The present invention relates to modified opiorphin peptides as new inhibitors of metallo-ectopeptidases.
2. Description of the Related Art
Zinc metal ectopeptidases control the receptor-dependent activity of neural and hormonal mediators involved in the regulation of important physiological functions in mammals. They are located at the surface of cells in nervous and systemic tissues and catalyze postsecretory processing or metabolism of neuropeptides and regulatory peptides (Rogues, B P, Noble, F, Dauge, V, Fournie-Zaluski, M C & Beaumont, A. (1993) Pharmacol Rev 45, 87-146. Turner, A J, Isaac, R E & Coates, D. (2001) BioEssays 23, 261-269).
Prominent among these neuronal and/or hormonal peptide signals are substance P (SP) and enkephalins, which are implicated in the receptor-dependent modulation of behavioral adaptive responses to stressful or threatening environmental stimuli. They notably regulate spinal processing of nociceptive information and analgesic mechanisms, emotional and/or motivational responses, anxiety, aggression, and neuroimmune inflammatory phenomena (Dickenson, A H. (1995) Br J Anaesth 75, 193-200. Sora, I, Takahashi, N, Funada, M, Ujike, H, Revay, R S, Donovan, D M, Miner, L L & Uhl, G R. (1997) Proc Natl Acad Sci USA 94, 1544-1549; Konig, M, Zimmer, A M, Steiner, H, Holmes, P V, Crawley, J N, Brownstein, M J & Zimmer, A. (1996) Nature 383, 535-538; Filliol, D, Ghozland, S, Chluba, J, Martin, M, Matthes, H W, Simonin, F, Befort, K, Gaveriaux-Ruff, C, Dierich, A & LeMeur, M, et al. (2000) Nat Genet. 25, 195-200).
Because of the physiological importance and the critical role of zinc ectopeptidases in modulating the functional potency of downstream neuronal and hormonal signals, it is essential to focus on what controls their activity and, as a consequence, the overall regulatory cascade. The discovery of upstream regulators of ectopeptidase activity also is exciting from physiopathological and therapeutic points of view because of the potential for developing new candidate drugs.
A brain-specific heptapeptide named spinorphin was isolated and characterized from bovine spinal cord based on its inhibitory activity toward enkephalin-degrading ectoenzymes, such as neutral endopeptidase (NEP; EC 3.4.24.11 [EC]) and aminopeptidase N (AP-N; EC 3.4.11.2 [EC]) (Nishimura, K & Hazato, T. (1993) Biochem Biophys Res Commun 194, 713-719; Yamamoto, Y, Ono, H, Ueda, A, Shimamura, M, Nishimura, K & Hazato, T. (2002) Curr Protein Pept Sci 3, 587-599). In addition, we characterized rat sialorphin, a peptide mediator involved in adaptation to environmental changes in rat. Rat sialorphin is an endocrine peptide signal whose expression is activated by androgen regulation and whose secretion is stimulated under adrenergic-mediated response to environmental stress in male rats. It is a physiological inhibitor of the membrane-anchored rat NEP activity and is a powerful inhibitor of pain sensation in rats (Rougeot, C, Rosinski-Chupin, I, Njamkepo, E & Rougeon, F. (1994) Eur J Biochem 219, 765-773; Rougeot, C, Vienet, R, Cardona, A, Le Doledec, L, Grognet, J M & Rougeon, F. (1997) Am J Physiol 273, R1309-R1320.; Rougeot, C, Rosinski-Chupin, I & Rougeon, F. (1998) in Biomedical Reviews eds. Chaldakov, G N & Mathison, R. (Bulgarian-American Center, Varna, Bulgaria,) Vol 9, pp. 17-32; Rosinski-Chupin, I, Huaulme, J F, Rougeot, C & Rougeon, F. (2001) Endocrinology 142, 4550-4559; Rougeot, C, Messaoudi, M, Hermitte, V, Rigault, A G, Blisnick, T, Dugave, C, Desor, D & Rougeon, F. (2003) Proc Natl Acad Sci USA 100, 8549-8554).
Previously we demonstrated that human Opiorphin native peptide (QRFSR-peptide (SEQ ID NO: 43)), the first characterized in human to date, is an efficient dual inhibitor of two enkephalin-inactivating ectopeptidases, neutral endopeptidase NEP (EC 3.4.24.11) and aminopeptidase AP-N (EC 3.4.11.2) (Wisner et al. Proc Natl Acad Sci USA, November 2006, 103(47): 17979-84).
Opiorphin peptide derivatives have been described previously, see, e.g., Wisner et al. Proc Natl Acad Sci USA, November 2006, 103(47): 17979-84 and has the basic peptide sequence as QRFSR (SEQ ID NO: 1).
Thus, this sequence and the sequence defined by the following formula may be modified: X1-X2-Arg-Phe-Ser-Arg (SEQ ID NO: 2), wherein X1 represents H atom or a Tyr amino acid, X2 represents Gln or Glp when X1 is H, or X2 represents Gln when X1 is Tyr or Cys. Preferred is QRFSR (SEQ ID NO: 1), YQRFSR (SEQ ID NO: 3), and/or CQRFSR (SEQ ID NO: 4) with QRFSR (SEQ ID NO: 1) most preferred. It is understood that Glp is pyroglutamate, Tyr or Y is Tyrosine, Gln or Q is glutamine, Arg or R is Arginine, Phe or F is Phenylalanine, Ser or S is Serine, and Cys or C for Cysteine. These peptides have been described in the international patent application published as WO2005090386.